1. Field of the Invention
The present invention relates to fluid flow measuring devices, and particularly to a clamp-on ultrasonic fluid flow meter system with improved accuracy.
2. Description of the Related Art
There is a considerable increase in the trend of using Clamp-On Metering products within building services and process industries. A clamp-on metering system consists of an ultrasonic transmitter and an ultrasonic receiver, which are mounted on the outer wall of the pipe carrying a flow of fluid. The measuring concept is based on transmitting an ultrasonic signal across the moving fluid, then receiving it, modified, after it encounters the fluid flowing in the pipe, and then processing the received signal to derive parameters of interest to calculate fluid flow velocity or volumetric flow rate. In such a metering system, a persistent problem has been how to attenuate a structural borne ultrasonic signal component that appears as noise over the fluid borne ultrasonic signal component used in measuring the fluid flow. This is particularly a problem when the fluid is in the gaseous state, which produces a weak signal when irradiated by ultrasonic waves, so that the weak signal reflection of the incident ultrasonic wave may be lost in or modified by the structural noise propagated in the pipe.
Although many techniques have been tried, none of these techniques have been entirely successful in overcoming structural pipe noise when using a clamp-on ultrasonic fluid flow meter. Thus, a clamp-on ultrasonic fluid flow meter system solving the aforementioned problems is desired.